A. Field
The invention relates to an apparatus and a method for testing of sensors for documents of value and a pertinent test medium.
B. Related Art
Apparatuses for processing documents of value in particular are required for processing bank notes, in order to for example check bank notes as to special authenticity features and quality properties. Forgeries and bank notes worn out by use are sorted out. Apparatuses for processing documents of value in principle can also be used for checking any other type of documents of value, for example for checking identity documents, credit cards, check cards, tickets and the like.
Checking the documents of value is effected with the help of a plurality of different sensors depending on the value document property to be checked. The sensors are checked at temporal intervals with respect to their correct functional ability, adjustment and/or calibration. Such a check usually is carried out with the help of special test media. “Test media” within the meaning of the present invention are such aids for checking the functional ability, adjusting and/or calibrating which have defined reference properties measurable by the sensors to be tested.
Such test media are known e.g. from EP 0731737 B1 or WO 03/036572 A2.
According to EP 0731737 B1 a reference device with optical reference surface is provided for calibrating an optical sensor for documents of value, the reference surface being displaceably mounted in relation to the optical sensor, so that different areas of the reference surface can be measured.
This reference device is an integral part of a checking device for documents of value and therefore cannot be used for other checking devices.
According to WO 03/036572 A2 functionally testing, adjusting and/or calibrating the sensors of a bank note processing apparatus is effected with the help of test media, which for checking, adjusting and/or calibrating one or a plurality of sensors bear specific features, which the bank note processing apparatus, however, recognizes and differentiates only through a machine-readable identification. In the bank note processing apparatus are stored pieces of information for each identification about which sensor with respect to which property is to be checked, adjusted and/or calibrated with the help of the test medium. Additionally, the measured sensor data concretely determined in the test runs are compared with measured sensor data which were determined in earlier test runs and/or when putting into operation the bank note processing apparatus, in order to determine a trend of the sensor properties and to be able to replace the sensor in time.
These test media, too, cannot readily be used in other bank note checking apparatuses, because in other bank note checking apparatuses, too, the respective pieces of information pertinent to the identification must be stored, namely which sensor with respect to which property is to be tested with the help of the respective test medium.
It is therefore the problem of the present invention to provide an apparatus and a method for testing of sensors for documents of value and a pertinent test medium, which permit a simple use of the test media even for testing different sensors.